Pen holder



FIG. 1 is a front elevational view of a pen holder showing my new design;

FIG. 2 is a right side elevational view, the left side being a mirror image thereof;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a front elevational view, the writing instrument depicted by means of broken lines being shown for illustrative purposes only and forming no part of the claimed design. 

The ornamental design for a “pen holder”, as shown and described. 